RONNY DEILA maintained that Celtic still have a chance of scoring against Inter Milan in the San Siro and reaching the last 16 of the Europa League, but he acknowledged they will need to defend far better than they did in last night's 3-3 draw at Parkhead.

The Celtic manager described the utterly absorbing first leg as the most unbelievable match he had been involved in as a manager.

John Guidetti's first goal since November thrilled a 60,000 crowd by delivering a Celtic equaliser with one of the last kicks of the game.

Inter Milan had capitalised on poor defending to go 2-0 up after 13 minutes and 3-2 ahead after a terrible, uncharacteristic mistake by goalkeeper Craig Gordon just before half-time.

Stuart Armstrong and a Hugh Campagnaro own goal helped give Celtic hope for next Thursday's second leg but they will almost certainly need to produce an unlikely win in Milan and Deila acknowledged that on the evidence of the first 90 minutes, that would require the team's best performance since he took over last summer.

When asked if he had experienced a night like it, he said: "Nothing near to it. It was an unbelievable football match with an unbelievable atmosphere. I am so proud of the boys. They were two down early in the match and it's so hard to get back, especially against an Italian team.

"We had talked about being brave, wanting the ball, trying to attack and create things, and that's why I am very proud. We caused them problems and we got a result in the end.

"But of course we wanted a better result and we could have had one if we hadn't given them too easy goals.

"I believe we can score in the San Siro. The most important thing is that we can't concede as many as we did today.

"We have a good chance of scoring but defensively we need to be much better than we were today. It is going to be very tough.

"We will have to be a bit lucky and put together the best performance we have done so far under my command. So it's going to be tough but it is possible. We are looking forward to the game."

Deila praised Guidetti, whose form and confidence had fallen away over recent months, but as a late substitute he made the sort of dramatic impact which characterised his early Celtic form. "He has had good focus lately, he's trained well, and when you train well you get your results. He had a good performance when he came on and scored a good goal as well."

As for Gordon, whose judgement was at fault for Inter's first goal as well as their third, Deila referred to his goalkeeper's excellent earlier European displays: "We wouldn't be here if it wasn't for him, we would have a Thursday off if it wasn't for him. He was unlucky today but the fans when they called his name after conceding the last goal, that is team spirit and I really, really appreciated that.

"That helped everybody and we got back into the game and a lot of that was because of the fans."

Inter manager Roberto Mancini said: "We started the game very well and scored two goals. After that we thought it would be an easy game. But Celtic are a good team. In the end it is a good result. Maybe we start the next game with an advantage, but we will need to play a good game."